A pathbreaking nerve-stimulating therapy can be highly beneficial for people with severe, treatment-resistant depression, and can significantly improve mood, quality of life, and their ability to complete daily tasks after a year, according to a large national trial led by Washington University School of Medicine in St. Louis. The therapy, involving nearly 500 participants, offers hope for those who have struggled to find relief through conventional treatments. The findings were published on December 18 in a pair of papers in the journal Brain Stimulation.
The participants were picked from 84 sites across the United States and all of them suffered from severe depression that could not be treated effectively with medication or other approaches. Another part of the study is still ongoing and addresses bipolar depression.
In this study, three quarters of the participants or 75% were so affected by depression that they were unable to work while 40% had a history of at least one suicide attempt. Each participant was implanted with a device that stimulates the left vagus nerve (which sends important information from different internal organs to the brain) but only half the devices were turned on.
Researchers monitored participants' progress using several validated assessment tools. Although the primary tool showed no notable differences between the on and off groups, many other measures highlighted significant benefits from the device's use.
“What’s really important here is that the patients themselves were reporting that their lives were improving,” Dr. Charles Conway professor of psychiatry and director of the Center for the Advancement of Research in Resistant Mood and Affective Disorders at Washington University in St. Louis said in a news release. “And the nice thing about vagus nerve stimulation, we know from other studies, is that when the patient responds, the effects usually stick.”
“Then we gave them two months to, what we call, titrate up their current,” Conway said. “A certain amount of current is optimal for getting an antidepressant response.”
In the course of next 10 months where the participants were evaluated monthly on their depression symptoms like quality of life and other functional outcomes, the trial didn’t meet its primary goal, which was for the Montgomery-Asberg Depression Rating Scale, or MADRAS, to show more improvement in the active VNS group compared to inactive VNS group. The MADRAS scale is one of the gold standard scales for evaluating individual symptoms that combine into depression.
However, the trial achieved its secondary objectives, showing improvements in depressive symptoms, daily functioning, and quality of life. These findings were based on three rating scales evaluated by on-site clinicians, patients, and independent off-site raters who were unaware of which participants had activated devices.
In all, 18% of active VNS patients reported improvement in their symptoms by at least 50%, Conway said, 53% of the active treatment group experienced progress in quality of life.
Experts noted that most of the improvements occurred during the final three months of the 10-month treatment period, which was expected since VNS therapy has a cumulative effect.
The study also sheds light on the placebo effect of the of the trial as around 16% of those in the inactive VNS group also reported antidepressant effects in the last few months, while the researchers thought it would be around 10%.
“Participants may have been positively anticipating device activation at the 1-year time point, or ‘placebo’ effects were accentuated by foreknowledge of the trial duration and awareness that benefits typically accrue with VNS only after several months of treatment,” according to the study.
At the end of the story, the inactive group's devices were also turned on so they could also experience positive effects from the treatment.
What is the vagus nerve?
The vagus nerve, also known as cranial nerve X, is the longest of the cranial nerves and gets its name from the Latin word “wandering” because it extends throughout the body, reaching the chest, abdomen, and pelvis. It plays a crucial role in several important bodily functions, including regulating heart rhythm and digestion. The vagus nerve has different parts and sends information to the brain.
What is vagal nerve stimulation
Vagal nerve stimulation (VNS) is an FDA-approved treatment for severe treatment-resistant depression (TRD). The VNS device is surgically implanted in the chest wall and wrapped around the vagus nerve in the neck. It sends electrical signals to the left side of the vagus nerve in the neck, which activates brain pathways that help regulate mood.
Vagus nerve stimulation can help increase the release of positive brain chemicals such as serotonin and norepinephrine, which help regulate mood and are found to be low in people with depression.
It also helps control inflammation in the body which has been linked to depression. The treatment empowers the brain to become more adaptable and strong as it helps form new connections.
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